[PATCH 6/7] gpio: Add new gpio-macsmc driver for Apple Macs

[Sven Peter]

On Tue, Sep 6, 2022, at 15:19, Russell King wrote:
> From: Hector Martin <marcan at marcan.st>
>
> This driver implements the GPIO service on top of the SMC framework
> on Apple Mac machines. In particular, these are the GPIOs present in the
> PMU IC which are used to control power to certain on-board devices.
>
> Although the underlying hardware supports various pin config settings
> (input/output, open drain, etc.), this driver does not implement that
> functionality and leaves it up to the firmware to configure things
> properly. We also don't yet support interrupts/events. This is
> sufficient for device power control, which is the only thing we need to
> support at this point. More features will be implemented when needed.
>
> To our knowledge, only Apple Silicon Macs implement this SMC feature.
>
> Signed-off-by: Hector Martin <marcan at marcan.st>
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>

Reviewed-by: Sven Peter <sven at svenpeter.dev>